package demo03;

class Solution {
    public int peakIndexInMountainArray(int[] arr) {
        int left = 0;
        int right = arr.length -1;
        while(left < right){
            int mid = left + (right - left + 1) / 2;
            if(arr[mid] >= arr[mid-1]) left = mid;
            else right = mid - 1;
        }
        return left;
    }

}